1. Field of the Invention
Aspects of the present invention relate to a battery management system. More particularly, aspects of the present invention relate to a battery management system used in a vehicle using electrical energy, and a driving method thereof.
2. Description of the Related Art
Vehicles that use internal combustion engines fueled by gasoline or heavy oil have caused serious air pollution. Accordingly, companies have made various efforts to develop electric and hybrid vehicles to reduce air pollution.
An electric vehicle uses a battery motor operating by electrical energy output from a battery. Since the electric vehicle is primarily driven by the battery, which is formed out of one battery pack including a plurality of rechargeable and dischargeable secondary cells, there is merit in that the electric vehicle does not emit emission gases and makes less noise.
The term “hybrid vehicle” commonly refers to a gasoline-electric hybrid vehicle that uses gasoline to power an internal-combustion engine and an electric battery to power an electric motor. Recently, companies have developed various kinds of hybrid vehicles, including hybrid vehicles using an internal-combustion engine and fuel cells and hybrid vehicles using a battery and fuel cells have been developed. The fuel cells directly obtain electrical energy by generating a chemical reaction while hydrogen and oxygen are continuously provided.
Since companies are increasing the number of rechargeable cells used in hybrid vehicles to improve a power source of the vehicles, and since the rechargeable cells directly affect the performance of the vehicle, it is important to increase the performance of the respective battery cells. In order to increase performance, hybrid vehicles should include a battery management system (BMS) to measure voltages of the respective cells and the voltage and current of an entire battery including the respective cells, and to efficiently manage a charging and discharging lifespan.
Particularly, internal resistance of the battery reduces an output of the battery and deteriorates the performance of the battery, and is used as a reference to determine the lifespan and a state of health (SOH) of the battery. In addition, the internal resistance varies according to a temperature of the battery and a state of charging (SOC). Accordingly, when the SOC is within an SOC area in which a variation of the internal resistance is minimized for a given battery temperature, the battery internal resistance may be more precisely detected.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.